ASSIST is Russian electronic payments provider, founded in 1998. Company start coincided with Russian eCommerce market developing, and electronic payments industry launching.
Please find more information about how to install plugins here.
The plugin is provided absolutely for free and includes source code. Find the project Github repository here for version 4.40.
You can also find the project Github repository here for previous versions.
Note: This plugin was originally developed by nopCommerce team. And now it's upgraded and maintained by nopStation.